The error dialogues that Windows produces do not always give an obvious clue to the problem, but they should be able to give you some useful information which you can use to look for a solution. You will need to find the name of the module causing the error.

Click the hyperlink and look for the module causing the error.

It is the ModName variable that you need to know, in this case ~df394b.tmp.
You could also just get 'Start.exe caused an illegal operation and needs to close', 'Start.exe caused an access violation' or 'Fatal acception'. In these cases there should be a button to view more information about the error. This will likely open a window full of seemingly random characters but at the top somewhere you should see a module name.
See Also: Fatal Error!